Juhl, who's been practicing his craft for a couple decades, worked all day on Saturday, collecting just the right stones on Sugarloaf Beach on Highway 61, delicately arranging them like God's Jenga pieces.

Once they were aligned just so, Juhl would step away, admiring his work with his own eyes and a camera. Then he'd deconstruct the pieces and move on, same as he always has since dabbling in this idiosyncratic pursuit.

Tired after eight hours' work, Juhl planned to head back to the cabin to sleep, before driving back to the Twin Cities, where he lives, and works as a databse administrator for Delta Air Lines.

Then he spotted a great rock. Big, about the size of a human skull, oblong, rounded along most of its edges, and with just the right imperfection.

"That white one on the top, it had a little divot in the side," Juhl says. "That’s what I use."

Juhl couldn't walk away yet.

Like all other pieces he remembers, this one came together like a jigsaw puzzle that sought its solver's touch. He steadied the first rock -- maybe the size of an orange -- then a smaller one on top of it, and a slightly larger one on top of that. Then came the effortful trick of getting the crown jewel on top of three smaller base pieces.

Those, Juhl held in place, as he gently rolled up the top stone, and repeatedly worked at setting it -- rolling, twisting, adjust weight -- until it was in place. "There are a lot of interdependencies," he says. Askew, at even a slight remove, it finally felt balanced after some 20 minutes of trying. He stepped away, bracing.

"It was small," Juhl says. "The whole thing was probably 12 inches high. It was so freaking delicate. When I got to let go, I was really surprised it stood more than few seconds."

In the memory of the online world, it will stand far longer than that. Juhl has posted his photos to his own website, and to Reddit's photo sharing site imgur, before. None has ever received so much attention: His posting on Sunday morning has been viewed more than 1.6 million times.

Juhl is proud of a lot of his other constructions.

But he's glad that his most popular piece is also one of his personal favorites.

"I really like the colors, the shapes of those rocks," he says. "The contact points are very small and visible. That’s important. In that regard, it was successful in that way. The rocks, the shape of the whole thing -- I kind of like the composition."

Throughout his years as a rock-stacker, Juhl has adhered to a strict hiker's "leave no trace" policy, either setting his stones back after he was finished or watching them fall in a wind gust moments after he'd taken their photo. This was the one time he let his sculpture stand.

He knew the gusts off Lake Superior would inevitably knock down this intricate tower. He "didn't have the heart" to destroy it himself, save the slight chance some stranger might happen upon it on this most perfect day.

"That's what I really love about this whole activity," Juhl says, "is to be absolutely on the line of impossibility. This one, it’s right on the edge, just a wisp of wind away."